Method and apparatus for heating work pieces

ABSTRACT

A method and apparatus for heating work pieces, especially motor armatures to degrade the insulation thereon for facile removal of the windings. The apparatus includes an annular combustion chamber, positioned to surround the work piece, enclosing it in a work piece receiving space. A combustion pipe provides combustion flame to the chamber and a combustion exhaust pipe exhausts the products of combustion from the chamber. Also, ports connect the work piece receiving space with the combustion chamber to vent the volatile combustible material with the products of combustion. Preferably the exhaust pipe vents to an afterburner chamber where complete combustion of the products is accomplished. Other features are also disclosed.

United States Patent [191 Heran METHOD AND APPARATUS FOR HEATING WORK PIECES [76] Inventor: Robert F. Heran, 1842 Dovna Dr.,

West Lake, Ohio 44145 [22] Filed: June 19, 1972 {21 1 Appl. No.: 263,959

[52] U.S. Cl... 432/6, 432/72 51 Dec. 4, 1973 Primary Examiner-John J. Camby Att0rneyWilliam N. Hogg 57 ABSTRACT A method and apparatus for heating work pieces, especially motor armatures to degrade the insulation thereon for facile removal of the windings. The apparatus includes an annular combustion chamber, positioned to surround the work piece, enclosing it in a work piece receiving space. A combustion pipe provides combustion flame to the chamber and a combustion exhaust pipe exhausts the products of combustion from the chamber. Also, ports connect the work piece receiving space with the combustion chamber to vent the volatile combustible material with the products of combustion. Preferably the exhaust pipe vents to an afterburner chamber where complete combustion of the products is accomplished. Other features are alsodisclosed.

12 Claims, 6 Drawing Figures PATENTEB DEC 4 I975 Ill METHOD AND APPARATUS FOR HEATING WORK PIECES RELATED PATENT This invention is related to U.S. Pat. No. 3,633,891, entitled Method and Apparatus for Heating Annular Work Pieces.

BACKGROUND OF THE INVENTION In the motor rebuilding art, the stators and/or rotors often have to be rewound. To accomplish this the old windings must first be removed. Said U.S. Pat. No. 3,633,891 discloses a method and apparatus for heating the statorto degrade the insulation on the wires rapidly, under controlled conditions, to facilitate the removal of the windings. This was a significant advance over the prior art methods of burning the insulation of the wires with a torch or other open fires or chemically treating the insulation to soften it. As pointed out in said patent these prior art methods were slow, inefficient, and in many cases contributed substantially to pollution. Further, there is no control over the temperature to which the rotors are subjected, and in many cases excess temperatures must be avoided to prevent damageto the rotor.

While the invention of U.S. Pat. No. 3,633,891 constitutes a major advance over these prior art teachings, it is only applicable to the stators, which are annular in shape, and not to rotors, which are cylindrical in shape, and hence rotors have continued to be treated by the prior art techniques. These techniques have the various disadvantages briefly noted above and fully described in said U.S. Pat. No. 3,633,891. I

SUMMARY OF THE INVENTION According to the present invention, a method and apparatus are provided for heating cylindrical work pieces such as motor stators, for degrading the insulation on the wire to facilely remove the windings. The apparatus includes a structure comprised of inner and outer cylindrical walls defining therebetween an annular combustion chamber. The inner wall defines an interior work piece receiving space configuredto receive a cylindrical body such as a motor rotor, and shield the rotor from direct combustion flame. There are means to provide combustion flame to the chamber and means to exhaust the combustion products from the chamber. Preferably, also, the device includes means to enclose the rotor within the receiving space and escape vents for allowing the volatile matter generated during heating to escape therefrom into the combustion chamber and pass off with the combustion products.

DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational view, somewhat diagrammatic, of the device of the present invention utilized in a heating furnace;

FIG. 2 is a side elevational view of the device show in FIG. 1;

FIG. 3 is aside elevational view, partially in section with parts broken away for clarity, of the device of this invention;

FIG. 4 is a front elevational view, partially in section with parts broken away for clarity, of the device of this invention;

FIG. 5 is a sectional view taken substantially along the plane designated by the line 5-5 of FIG. 3; and

FIG. 6 is a sectional view taken substantially along the plane designated by the line 6-6 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, a work piece heating device is shown incorporated in a heating furnace of the general type shown in said U.S. Pat. No. 3,633,891, although somewhat modified therefrom. As can be seen in FIGS. 1 and 2 the heat treating furnace includes a stationary cabinet 10 which cooperates with a roller mounted platform 12 to define the furnace. The stationary cabinet 10 includes a steel outer frame 14 with insulation 16 lining said frame. The frame is enclosed on three sides and the top, and the fourth side (the front) is closableby a vertically slidable door 18. An afterburner chamber 20 extends upwardly from the top of the cabinet 10, and disposed in the afterburner chamber is an afterburner 22 and air line 24. Volatile combustible products which enter the afterburner chamber 20 are substantially totally consumed by re gulating the afterburner 22 and the volume of air 24 in the line as is explained in said U.S. Pat. No. 3,633,891.

The roller mounted platform 12 includes a top 30 lined with insulation and supported by legs 32 which in turn are mounted on rollers 34. The platform 12 .thus can be rolled into and out of the cabinet 10 and when it is disposed therein as shown in FIG. 1 it forms the bottom of the heating furnace. Thus when the door 18 is closed and the platform 12 is in the cabinet there is essentially a completely enclosed heating furnace structure.

The platform 12 is provided with a burner tube 36 which is mounted on a support 38 beneath the top 30. The burner tube 36 is supplied by a gas line 40 and an air line 42 which inturn are supplied by appropriate feed and control mechanisms designated by the rectangle 44. These are conventional and do not per se form any part of the invention and are hence only indicated as the rectangle 44. A spring loaded thermocouple 46 is also provided in the stationary cabinet 10 which is connected to the feed and control mechanism which will control the firing of the burner to control the heat supplied for the heating of the cylindrical work pieces, as will be described presently. The structure as has been described does not per se constitute a portion of the present invention, but rather it is prior art very similar to the device as shown in U.S. Pat. No. 3,633,891. In fact, the present invention is adapted to operate within this structure so that the same structure can operate bothfor heating motor stators and motor armatures and rotors.

The specific heating device of the present invention, designated by the reference character 48, includes a cylindrical outer shell 50 and a cylindrical inner shell 52 which are maintained in spaced relationship by annular rings 54 at opposite ends thereof, which rings 54 have flanges 56'. An annular combustion chamber 58 is defined between the outer shell 50 and the inner shell 52 and sealed at the ends bythe rings 54. Insulation 59 surrounds the outer shell 50. v

A combustion entry pipe60 extends in one direction chamber. The openings 62 and 66 are spaced approximately I80 from each other. The device is normally utilized in the position shown in FIGS. 1 through 4 with the combustion entry pipe 60 extending generally downwardly and the combustion exhaust pipe extending generally upwardly. Hence downward and upward directions or positions of the device will be designated with reference to the device in its normally as used position. The shells 50, 52, the annular rings 54, and the pipes 60 and 64 are all made of high temperature resistant material such as stainless steel to withstand the heat of combustion.

The upper side of the inner shell 52 is provided with a plurality of volatile matter escape ports 68. The escape ports 68 allow communication between the cylindrical armature receiving space 70 defined within the inner cylindrical shell 52 and the combustion chamber 58 for the discharge of any volatile combustionable matter.

The device is specifically adapted to heat an armature designated generally as A. (The terms armature and rotor are used herein synonymously and interchangeably). Armatures conventionally have a core CR mounted on a shaft S extending therethrough. Windings W normally communicate with commutator CM. In order to utilize the device the core CR of the armature is disposed within the cylindrical space 70 with the shaft S extending on opposite sides thereof. The device is placed on the top 30 of the platform 12 with the combustion entry pipe 60 surrounding the burner tube 36 and'carried by the support 30 which mounts the burner tube. The armature is supported out of contact with the inner cylindrical shell 52 by means of a pair of adjustable support members 72 supporting opposite ends of the shaft S as shown in FIGS. 1 and 2. In order to enclose the core at the ends as well as the circumference thereof, the device is provided with flexible heat resisting covers 74 at opposite ends thereof. These flexible heat resistant covers 74 are secured to the flanges 56 of the annular rings 54 by means of band clamps 76. The covers 74 are formed of a flexible insulating'material 80, such as Kaowool (Manufactured by Babcock & Wilcox) sandwiched between a double outer layer of mesh inconel wire 82 and a double inner layer of mesh inconel wire 84. The covers 74 are formed with wedged or pie shaped sections 86 as shown in FIGS. 4 and 5 so that the sections may be peeled back to accept the rotor and allow it to be removed, while having the ability to be formed around the end to substantially enclose the ends.

In utilizing the device of the present invention to degrade the insulation on motor rotors, the device is place on the platform 12 as shown in FIGS. 1 and 2 with the combustion entry pipe 60 supported by the support 38 surrounding the burner tube 36. The armature A is then placed into the armature receiving space 70 with the shaft S extending from opposite ends thereof. The wedge shaped pieces 86 of the covers 74 are securely tucked around the shaft to eflectively seal the core of the rotor within the space. Normally the windings are cut from the commutator CM to prevent conductive heat transfer, since it is desirable to keep both the shaft and the commutator as cool as possible during the heating operation to degrade the insulation. The shaft is supported at opposite ends by support members 72, these being adjusted so that the core CR is out of contact with the inner cylindrical shell 52. This is the configuration shownin FIG. 2. With the device so supported the platform 12 can be rolled into the furnace and the thermocouple 46 will come in contact with the combustion exhaust pipe 64, the spring loading thereof allowing the thermocouple to retract as necessary but still maintain contact. If desired the door 18 may be closed, however, it is normally satisfactory to operate with this door open since the rotor is substantially enclosed within the device and the combustion chamber is enclosed so that the products of combustion will be dissipated to the afterbumer chamber. Also, as shown in FIGS. 1 and 2, a biforcated air pipe 88 is provided, having nozzles at the opposite ends thereof, the nozzles 90 being directed to blow air against the commutator at one end of the shaft and the shaft itself at the opposite end. The air pipe 88 is supplied with air from a source of compressed air (not shown) and is supported on any convenient means such as a pipe support member 92.

When the platform 12 has been moved within the enclosure the burner tube 36 can then be fired by the control mechanism with the combustion taking place in a combustion entry pipe 60 and the annular combustion chamber 58. It is to be understood that the flame itself may not reach entirely into the combustion chamber 58. However, the heat and combustion products from the burner do enter this chamber and hence the term combustion chamber as used is intended to include any type of chamber which is heated without there necessarily being actual open flame throughout the chamber itself, since as in the present case the open flame may well be confined only to the combustion entry pipe 60 or even just the lower portion thereof.) The firing of the burner will heat the walls 50 and 52 of the combustion chamber 58. The inner wall 52 will radiate directly to the core CR of the armature causing it to heat rapidly in an efficient heat exchange around the entire 360 outer surface thereof. Also the covers 74 enclose the armature, excluding the entrance of any substantial amount of air. Thus there is an indirect rapid heating of the core, in an oxygen starved atmosphere which will cause a changing, degrading and volatilization, but not a burning of the insulation material of the windings. The amount of heat generated will depend upon the temperature to which the combustion chamber is heated and the length of time which it is held and this in turn can be controlled by controlling the firing rate of the burner 36. The firing rate of the burner 36 in turn is automatically-controlled by the thermocouple 46 in contact with the combustion exhaust pipe 64 which also is heated. By controlling the temperature of this pipe the temperature of the combustion chamber is also controlled. This will allow a controlled heating of the core and when heated to the proper temperature will cause a degradation and volatilization of the insulation on the armature winding without damage to the other parts. The volatilized matter will pass through the volatile matter escape ports 68 and will mix with the combustion products from the burner 36 in the combustion exhaust pipe 64. These products in turn will pass to the afterbumer chamber 20 where they will be substantially completely burned by the burner 22 and I the excess of air supplied by the air pipe 24. This will then pass off into the atmosphere as completely com- 4 busted exhaust material without unburned hydrocarbons or-carbon monoxide or other volatile combustion products thereby contributing to pollution control.

As was indicated above, it is often necessary to keep the temperature of the commutator substantially lower than that needed to degrade the insulation. When this is necessary it can be accomplished by means of the air pipe 88 and nozzles 90 directing a flow of cool air against the shaft S and commutator CM. This flow of air will reduce the amount of heat conduction from the core to the shaft and then to the commutator, thereby cooling the commutator while still allowing the heat to be applied to the core. The flow rate of the air can be regulated to provide the necessary cooling characteristics. Also, the insulation 59 shields the commutator CM from direct radiation thus aiding in keeping the temperature down. For instance, with many armatures it is necessary to keep the commutator temperature below 350 F and the core below 750 F and with a device of this invention such temperatures have been maintained and armatures satisfactorily treated.

When the operation is complete the burner is turned off and the platform can be removed from the stationary cabinet and the rotor removed from the device and the windings easily removed after the insulation thereon has been degraded.

This invention has been described in conjunction with heating cylindrical work pieces, and for this the annular combustion chamber has been greatly formed on concentric circular shells. However, other shaped work pieces could be involved in which case different shaped combustion chambers could be utilized. Hence annular as used herein includes surrounding chamber shapes other than circular.

What is claimed is:

l. A device for evenly heating a work piece from the outer surface comprising, structure means having inner and outer cylindrical walls, defining therebetween an annular combustion chamber, said inner wall defining an interior work piece receiving space configured to receive a generally cylindrical work piece and having its axis generally horizontally disposed, means to provide combustion flame to said chamber, means to exhaust the combustion products from said chamber and openings through said inner wall connecting said interior work piece receiving space with the combustion chamber.

2. The invention as defined in claim 1 wherein said means to provide combustion flame and said means to carry off combustion are pipes communicating with said chamber through the outer cylindrical wall.

3. The invention as defined in claim 2 further characterized by openings through said inner wall connecting said interior work piece receiving space with said combustion chamber.

4. The invention as defined in claim 1 further characterized by means to at least partially enclose the axial ends of said work piece receiving space with the work piece disposed therein.

5. The invention as defined in claim 3 wherein the openings through the inner wall and the pipe means to carry off the combustion products are located generally at the top of said annular structure.

6. The invention as defined in claim 1 further characterized by support means externally of said structure means to support the work piece within said work piece receiving space out of contact with said inner wall.

7. The invention as defined in claim 1 further characterized by means to control the temperature of said structure defining the combustion chamber.

8. A method of heating a work piece from the outer surface comprising the steps of,

providing an annular combustion chamber defined by inner and outer cylindrical walls and which inner wall defines an annular work piece receiving space,

supporting said work piece within said space, providing combustion flame to said chamber exhausting combustion products from said chamber and passing off the volatile matter generated during heating of the work piece with the combustion products.

9. The invention as defined in claim 8 further characterized by at least partially enclosing the ends of said space around said work peice.

10. The invention as defined in claim 8 wherein said work piece is a motor rotor, and wherein the rotor has a core in said work piece receiving space and shaft means internally thereof, further characterized by cooling said shaft means during heating of said core.

11. The invention as defined in claim 10 wherein said cooling is accomplished by blowing air on the shaft.

12. The invention as defined in claim 8 further characterized by controlling the temperature of said combustion chamber to thereby regulate the temperature of said work piece.

UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION Patent No. ,776,687 Dated December 4, 1973 Inventor-(5) Robert F, Heran It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 63, "60" should read -50 Column 3, line 52, "place" should read --placed--,

Column 6, line 39, "internally" should read --externally-- Signed and sealed this 23rd day of July 197A.

(SEAL) Attest:

McCOY Mo GIBSON, JR. Q C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM DC 6o376 P9 a u.s. sovsrmmzm PRINTING OFFICE: I969 0-366-334 

1. A device for evenly heating a work piece from the outer surface comprising, structure means having inner and outer cylindrical walls, defining therebetween an annular combustion chamber, said inner wall defining an interior work piece receiving space configured to receive a generally cylindrical work piece and having its axis generally horizontally disposed, means to provide combustion flame to said chamber, means to exhaust the combustion products from said chamber and openings through said inner wall connecting said interior work piece receiving space with the combustion chamber.
 2. The invention as defined in claim 1 wherein said means to provide combustion flame and said means to carry off combustion are pipes communicating with said chamber through the outer cylindrical wall.
 3. The invention as defined in claim 2 further characterized by openings through said inner wall connecting said interior work piece receiving space with said combustion chamber.
 4. The invention as defined in claim 1 further characterized by means to at least partially enclose the axial ends of said work piece receiving space with the work piece disposed therein.
 5. The invention as defined in claim 3 wherein the openings through the inner wall and the pipe means to carry off the combustion products are located generally at the top of said annular structure.
 6. The invention as defined in claim 1 further characterized by support means externally of said structure means to support the work piece within said work piece receiving space out of contact with said inner wall.
 7. The invention as defined in claim 1 further characterized by means to control the temperature of said structure defining the combustion chamber.
 8. A method of heating a work piece from the outer surface comprising the steps of, providing an annular combustion chamber defined by inner and outer cylindrical walls and which inner wall defines an annular work piece receiving space, supporting said work piece within said space, providing combustion flame to said chamber exhausting combustion products from said chamber and passing off the volatile matter generated during heating of the work piece with the combustion products.
 9. The invention as defined in claim 8 further characterized by at least partially enclosing the ends of said space around said work peice.
 10. The invention as defined in claim 8 wherein said work piece is a motor rotor, and wherein the rotor has a core in said work piece receiving space and shaft means internally thereof, further characterized by cooling said shaft means during heating of said core.
 11. The invention as defined in claim 10 wherein said cooling is accomplished by blowing air on the shaft.
 12. The invention as defined in claim 8 further characterized by controlling the temperature of said combustion chamber to thereby regulate the temperature of said work piece. 